I have a question regarding intercepting the system call from a guest kernel on hypervisor. I am using xen-4.0.1 with a PV-guest.
To disable the fast system call which bypasses the hypervisor, I first comment out this lines in the file
If (cur.vector == 0x80)
/* init_int80_direct_trap(curr); */
To verify this, when I boot the kernel, I add printk and see that init_int80_direct_trap is not executed.
Then in the function in the same file as above, do_guest_trap, I add a printk to trap the system call from guest kernel
Static void do_guest_trap…
If (trapnr == 0x80)
printk("System call from guest");
However, when I run some program in the guest kernel to issue some system call, the hypervisor does not print out the message. Can anyone help on this? Thanks.